1. Field of the Invention
The invention relates to a pile-driving ram for driving elongated objects into the ground comprising an impact weight adapted to reciprocate at least mainly in the direction of displacement of the elongated object during operation and to cooperate with an anvil arranged on the object to be driven into the ground.
2. Description of the Prior Art
In the conventional pile-driving rams the impact weight is formed by a single mass which is lifted each time during operation over a given distance, after which said mass is allowed to drop freely and, as the case may be, the mass may even be accelerated during its fall so that the impact weight strikes the anvil cooperating with the object to be driven with a given speed. Upon collision particularly heavy forces are, in general, generated for a very short time. These forces are often markedly higher than the force required to overcome the resistance experienced by the object in the ground. Due to this impact characteristic the useful effect of the stroke, that is to say the penetration increment per stroke is not satisfying. Therefore, in many cases there is a tendency to use the highest possible striking speeds still allowed for reasons of strength. In many cases it can, however, not be avoided that in given parts of the ram and/or in the object to be driven into the ground for example, a pile, critical stress will occur, which is detrimental to the lifetime of the parts concerned and to the safety of operation of the pile-driving ram.